Electromagnetic metamaterial suitable for high-voltage direct-current transmission line and preparation method thereof

Abstract

The invention relates to the technical field of high-voltage direct-current power transmission lines, in particular to an electromagnetic metamaterial suitable for a high-voltage direct-current power transmission line and a preparation method of the electromagnetic metamaterial. The invention discloses an electromagnetic metamaterial suitable for a high-voltage direct-current transmission line. The electromagnetic metamaterial comprises a continuous metal layer, a continuous dielectric layer and an annular magnetic bimetallic layer which are sequentially arranged from bottom to top, the continuous medium layer is a polyetherimide layer or a polyimide / nanoparticle composite layer; and the annular magnetic bimetallic layer is annular and is formed along the periphery of the continuous dielectric layer. According to the electromagnetic metamaterial suitable for the high-voltage direct-current power transmission line, the metal copper bottom layer, the flexible polyetherimide dielectric layer and the novel magnetic bimetal opening array top layer are adopted to form a sandwich structure, efficient and broadband electromagnetic wave absorption is achieved, and accurate measurement of a direct-current power transmission line magnetic field can be achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of high-voltage direct current transmission lines, and in particular to an electromagnetic metamaterial suitable for high-voltage direct current transmission lines and a preparation method thereof. Background Art

[0002] In the operation and maintenance of power systems, accurate magnetic field detection of transmission lines is crucial. Due to the complexity of the environment around transmission lines, such as nearby power facilities, wireless communication equipment, and lightning activities in the natural environment, electromagnetic waves of various frequencies and intensities are generated. These electromagnetic waves are superimposed on the magnetic field generated by the transmission line itself, forming a complex electromagnetic environment. In such an environment, traditional DC electromagnetic detection methods often have difficulty in accurately distinguishing the magnetic field of the transmission line itself from the magnetic field generated by the interference wave, which greatly reduces the accuracy of the detection results.

[0003] In order to improve the accuracy of transmission line magnetic field detection, effective measures must be taken to suppress or eliminate the influence of these interference waves. In recent years, with the rapid development of metamaterial technology, its application in the field of electromagnetic regulation has become increasingly widespread. Metamaterials can absorb and reflect specific interfering electromagnetic waves through their special structure and electromagnetic parameters, thereby retaining specific required and detectable electromagnetic waves, effectively improving the accuracy of transmission line magnetic field detection and providing more reliable data support for the operation and maintenance of power systems. Summary of the invention

[0004] The purpose of the present invention is to address the above-mentioned deficiencies in the prior art and to provide an electromagnetic metamaterial suitable for high voltage direct current transmission lines and a preparation method thereof.

[0005] The electromagnetic metamaterial of the present invention, which is suitable for high-voltage direct current transmission lines, comprises a continuous metal layer, a continuous dielectric layer, and an annular magnetic bimetallic layer arranged in sequence from bottom to top;

[0006] The continuous medium layer is a polyetherimide layer or a polyimide / nanoparticle composite layer;

[0007] The annular magnetic bimetallic layer is annular and is formed along the periphery of the continuous dielectric layer.

[0008] Furthermore, the continuous metal layer is made of copper.

[0009] Furthermore, the nanoparticles are barium titanate or\ and niobium carbonate.

[0010] Furthermore, the preparation method of the annular magnetic bimetallic layer includes the following steps: first, a stainless steel template with a desired annular pattern is accurately prepared by laser etching technology; then, the template is tightly fixed on the continuous dielectric layer by a clamp; then, the continuous dielectric layer with the template fixed is placed in an electrolytic cell, and copper sulfate is selected as the electrolyte solution, and electrolytic deposition is performed at an appropriate current density, so that annular metal copper wires are deposited at the annular opening; then, a magnetic bimetallic material solution is applied to the continuous dielectric layer with the annular metal wires deposited thereon, and the solution is dried and solidified; finally, the stainless steel template and the metal copper wires deposited on the template are removed by chemical corrosion by immersion in a dilute hydrochloric acid solution, thereby obtaining a magnetic bimetallic material layer with an annular opening array.

[0011] Furthermore, the magnetic bimetallic material is NiCo-MOF.

[0012] Furthermore, an electromagnetic metamaterial suitable for high-voltage direct current transmission lines is characterized in that: the preparation method of the polyimide / nanoparticle composite layer is to dissolve the nanoparticles in an organic solvent system, then add a polyamic acid solution for blending and stirring to obtain a precursor of the composite material, and finally obtain the polyimide / nanoparticle composite layer by a thermal imidization method.

[0013] Furthermore, the mass fraction of the nanoparticles is 5 to 20 wt%.

[0014] A method for preparing an electromagnetic metamaterial suitable for a high-voltage direct current transmission line as described above comprises the following steps:

[0015] S1. Preparing a continuous metal layer: cleaning the metal copper sheet and obtaining a uniform and continuous copper metal layer by using a copper electroplating process;

[0016] S2, preparing a continuous dielectric layer: selecting a predetermined ratio of nanoparticles and dispersing them in a chloroform organic solvent, then adding a polyamic acid solution, stirring and mixing them thoroughly, applying them on the continuous metal layer by a spray coating method, and drying to obtain a polyimide / nanoparticle composite layer as a continuous dielectric layer;

[0017] S3. Preparation of annular magnetic bimetallic layer: First, a stainless steel template with the desired annular pattern is prepared by laser etching technology and tightly fixed on the continuous dielectric layer; then, an annular metal wire is deposited by electrochemical deposition under appropriate copper sulfate solution and current density; then, the magnetic bimetallic material NiCo-MOF is dissolved in methanol solvent, coated on the continuous dielectric layer with the annular metal wire deposited, and dried and solidified; finally, the stainless steel template and the metal copper wire deposited on the template are immersed in a dilute hydrochloric acid solution to obtain an annular magnetic bimetallic layer.

[0018] The present invention proposes an electromagnetic metamaterial suitable for high-voltage direct current transmission lines, which uses a metal copper bottom layer, a flexible polyetherimide dielectric layer and a new magnetic bimetallic open array top layer to form a "sandwich" structure. The new magnetic bimetallic material is formed by in-situ self-assembly of cobalt and nickel. By optimizing the design and preparation process, efficient and wide-band electromagnetic wave absorption is achieved. An absorption peak with an absorption rate of 97.6% is generated at 0.185THz, realizing accurate monitoring of the magnetic field of the high-voltage direct current transmission line. At the same time, the electrical testing device of the present invention has an absorption rate greater than 80% in the frequency band of 0.165-0.196THz, which meets the low-frequency high absorption characteristics.

[0019] The present invention achieves accurate measurement of the magnetic field of a DC transmission line by optimizing the structural design of the bottom continuous metal layer, the middle continuous dielectric layer and the top annular opening array. The bottom continuous metal layer provides an electromagnetic shielding effect and acts as a bottom reflection surface, enhancing the multiple reflections and absorption of electromagnetic waves in the dielectric layer, thereby improving the accuracy of the measurement. By precisely controlling the thickness and shape of the metal layer, the propagation path of electromagnetic waves inside the electromagnetic metamaterial can be further optimized and the wave absorption efficiency can be improved. For example, a gradient thickness design can achieve more uniform electromagnetic wave absorption at different frequencies.

[0020] The continuous dielectric layer in the middle is made of polyetherimide (PEI) material with a relative dielectric constant of εr = 3.2, and the dielectric constant is dynamically adjusted by doping nanoparticles (such as barium titanate and niobium carbonate). This design enables the electromagnetic metamaterial to have more optimized electromagnetic wave absorption characteristics at different frequencies, thereby adapting to the magnetic field measurement needs of DC transmission lines under different working conditions.

[0021] The selection of PEI material not only ensures the mechanical strength and stability of the dielectric layer, but also optimizes the propagation path of electromagnetic waves inside the electromagnetic metamaterial through its specific dielectric properties, further improving the wave absorption efficiency. In addition, by doping 5 to 20wt% of a specific proportion of nanoparticles (such as barium titanate and niobium carbonate), the dielectric constant εr can be dynamically adjusted to have more optimized electromagnetic wave absorption characteristics at different frequencies. At the same time, the flexible properties of PEI materials enable electromagnetic metamaterials to adapt to line surfaces of different shapes, improving measurement flexibility. The propagation path of the electromagnetic field of the transmission line inside the electromagnetic metamaterial can also be further optimized by adjusting the thickness and dielectric constant of the continuous dielectric layer. For example, a multi-layer structure design can achieve more efficient electromagnetic wave absorption at different frequency bands.

[0022] The annular magnetic bimetallic layer adopts a new type of magnetic bimetallic material with excellent electromagnetic properties. It can more effectively capture and respond to the changes in the magnetic field generated by the DC transmission line, further improving the measurement accuracy.

[0023] By adjusting the thickness and dielectric constant of the continuous dielectric layer, as well as the size and shape of the annular opening array, the propagation path of the electromagnetic field of the transmission line inside the electromagnetic metamaterial can be further optimized to achieve more efficient electromagnetic wave absorption in different frequency bands. This tunability enables the present invention to be widely used in the magnetic field measurement of DC transmission lines of different voltage levels and capacities.

[0024] The material used in the present invention has good long-term stability and corrosion resistance, can maintain excellent electromagnetic properties in harsh environments, and ensure the accuracy and reliability of measurement results.

[0025] The implementation of the present invention not only promotes the application of electromagnetic metamaterials in the field of magnetic field measurement of DC transmission lines (such as Figure 1 It also provides new ideas and methods for the further innovation and development of electromagnetic metamaterial technology.

[0026] In addition to the magnetic field measurement of DC transmission lines, the present invention can also be expanded to be applied to the measurement and shielding fields of other electromagnetic environments, such as high-voltage substations, electromagnetic compatibility testing, etc., and has important practical value. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A schematic diagram of magnetic field control of an electromagnetic metamaterial suitable for high-voltage direct current transmission lines according to the present invention;

[0028] Figure 2 It is a schematic structural diagram of an electromagnetic metamaterial suitable for high-voltage direct current transmission lines of the present invention;

[0029] Figure 3 This is the surface structure SEM of the annular magnetic bimetallic layer;

[0030] Figure 4 is the absorption characteristic curve of Example 1;

[0031] 1. Continuous metal layer; 2. Continuous dielectric layer; 3. Annular magnetic bimetallic layer. DETAILED DESCRIPTION

[0032] The following are specific embodiments of the present invention and the accompanying drawings to further describe the technical solution of the present invention, but the present invention is not limited to these embodiments.

[0033] Preparation method of magnetic bimetallic material:

[0034] 3 mmol of terephthalic acid powder was ultrasonically dissolved in a mixed solution consisting of N, N-dimethylacetamide (128 ml), ethanol (8 ml) and water (8 ml). 1.5 mmol of cobalt nitrate hexahydrate and 1.5 mmol of nickel chloride hexahydrate were added, and after dissolution, 3.2 ml of triethylamine was quickly injected into the solution. Then, the solution was stirred for 5 minutes to obtain a uniform colloidal suspension. After that, the colloidal solution was ultrasonically treated for 8 hours continuously (53 kHz, temperature below 10 ° C) under closed conditions. Finally, the product NiCo-MOF was obtained by centrifugation, washed 4 times with ethanol, and dried at room temperature.

[0035] Example 1

[0036] A method for preparing an electromagnetic metamaterial suitable for a high-voltage direct current transmission line as described above comprises the following steps:

[0037] S1. Preparation of continuous metal layer: Clean and pretreat the metal copper sheet, and use copper electroplating process to obtain a uniform and continuous metal layer; the electroplating solution is 75g / L copper sulfate and the current density is 1.5A / dm 2 , the electroplating time is 5 minutes.

[0038] S2. Prepare a continuous dielectric layer: Select a predetermined ratio of nanoparticles (such as barium titanate or niobium carbonate) and disperse them in a chloroform organic solvent, then add a polyamic acid solution and stir and mix thoroughly to obtain a composite material precursor. Spray the composite material precursor onto the continuous metal layer and dry at 120°C to obtain a polyimide / nanoparticle continuous dielectric layer;

[0039] S3. Preparation of annular magnetic bimetallic layer: Prepare a metal copper wire template with an annular opening array by electrochemical deposition. Specifically, prepare a stainless steel template with the required annular pattern by laser etching; the continuous dielectric layer is used as a conductive substrate, and the stainless steel template is fixed on the continuous dielectric layer substrate by a clamp to make it in close contact, and then placed in an electrolytic cell, copper sulfate is selected as the electrolyte solution, and the power is turned on, with a current density of 120mA / cm 2 , the deposition time is 15min, and an annular metal wire is obtained; then the magnetic bimetallic material NiCo-MOF is dissolved in methanol solvent, coated on the continuous medium layer with the annular metal wire deposited, and dried and solidified at 80°C. One side of the annular opening array layer is immersed in 5% dilute hydrochloric acid, and the immersion is repeated for 25 to 30min, and the stainless steel template is removed to obtain an annular magnetic bimetallic layer.

[0040] Prepared as Figure 2 Electromagnetic metamaterials for high-voltage direct current transmission lines shown.

[0041] Surface structure SEM of NiCo-MOF annular opening array Figure 3 shown.

[0042] Example 2

[0043] The continuous dielectric layer is not doped with nanoparticles, and the rest is the same as in Example 1.

[0044] Comparative Example 1

[0045] The annular opening array 3 of the top layer is made of metal copper, and the rest is the same as in the first embodiment.

[0046] The absorption performance of Example 1 is as follows Figure 4 As shown, an absorption peak with an absorption rate of 97.6% is generated at 0.185THz, realizing accurate monitoring of the magnetic field of the high-voltage DC transmission line. At the same time, the electric detection device of the present invention has an absorption rate greater than 80% in the frequency band of 0.165-0.196THz, meeting the low-frequency high absorption characteristics.

[0047] The absorption properties of Examples 1, 2 and Comparative Example 1 are shown in Table 1

[0048]

[0049] For matters not mentioned above, the prior art applies.

[0050] Although some specific embodiments of the present invention have been described in detail through examples, those skilled in the art should understand that the above examples are for illustration only and are not intended to limit the scope of the present invention. Those skilled in the art to which the present invention belongs may make various modifications or supplements to the specific embodiments described or replace them in a similar manner, but they will not deviate from the direction of the present invention or exceed the scope defined by the attached claims. Those skilled in the art should understand that any modifications, equivalent substitutions, improvements, etc. made to the above embodiments based on the technical essence of the present invention should be included in the protection scope of the present invention.

Claims

1. An electromagnetic metamaterial suitable for high voltage direct current transmission lines, characterized in that: It includes a continuous metal layer, a continuous dielectric layer, and an annular magnetic bimetallic layer arranged in sequence from bottom to top; The continuous medium layer is a polyetherimide layer or a polyimide / nanoparticle composite layer; The annular magnetic bimetallic layer is annular and is formed along the periphery of the continuous dielectric layer.

2. The electromagnetic metamaterial suitable for high voltage direct current transmission lines according to claim 1, characterized in that: The continuous metal layer is made of copper.

3. The electromagnetic metamaterial suitable for high voltage direct current transmission lines according to claim 1, characterized in that: The nanoparticles are barium titanate or\ and niobium carbonate.

4. The electromagnetic metamaterial suitable for high voltage direct current transmission lines according to claim 1, characterized in that: The preparation method of the annular magnetic bimetallic layer comprises the following steps: first, a stainless steel template with a desired annular pattern is accurately prepared by laser etching technology; then, the template is tightly fixed on a continuous dielectric layer by a clamp; then, the continuous dielectric layer with the template fixed is placed in an electrolytic cell, and copper sulfate is selected as an electrolyte solution, and electrolytic deposition is performed at an appropriate current density, so that annular metal copper wires are deposited at the annular opening; then, a magnetic bimetallic material solution is applied to the continuous dielectric layer with the annular metal wires deposited thereon, and the solution is dried and solidified; finally, the stainless steel template and the metal copper wires deposited on the template are removed by chemical corrosion by immersion in a dilute hydrochloric acid solution, so as to obtain a magnetic bimetallic material layer with an annular opening array.

5. The electromagnetic metamaterial suitable for high voltage direct current transmission lines according to claim 1 or 4, characterized in that: The magnetic bimetallic material is NiCo-MOF.

6. The electromagnetic metamaterial suitable for high voltage direct current transmission lines according to claim 1, characterized in that: The preparation method of the polyimide / nanoparticle composite layer comprises dissolving the nanoparticles in a chloroform organic solvent system, then adding a polyamic acid solution for blending and stirring to obtain a precursor of the composite material, and finally obtaining the polyimide / nanoparticle composite layer by a thermal imidization method.

7. The electromagnetic metamaterial suitable for high voltage direct current transmission lines according to claim 6, characterized in that: The mass fraction of the nanoparticles is 5 to 20 wt%.

8. A method for preparing an electromagnetic metamaterial suitable for a high voltage direct current transmission line according to any one of claims 1 to 7, characterized in that: The steps include: S1. Preparing a continuous metal layer: cleaning the metal copper sheet and obtaining a uniform and continuous copper metal layer by using a copper electroplating process; S2, preparing a continuous dielectric layer: selecting a predetermined ratio of nanoparticles and dispersing them in a chloroform organic solvent, then adding a polyamic acid solution, stirring and mixing them thoroughly, applying them on the continuous metal layer by a spray coating method, and drying to obtain a polyimide / nanoparticle composite layer as a continuous dielectric layer; S3. Preparation of annular magnetic bimetallic layer: First, a stainless steel template with the desired annular pattern is prepared by laser etching technology and tightly fixed on the continuous dielectric layer; then, an annular metal wire is deposited by electrochemical deposition under appropriate copper sulfate solution and current density; then, the magnetic bimetallic material NiCo-MOF is dissolved in methanol solvent, coated on the continuous dielectric layer with the annular metal wire deposited, and dried and solidified; finally, the stainless steel template and the metal copper wire deposited on the template are immersed in a dilute hydrochloric acid solution to obtain an annular magnetic bimetallic layer.

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